Discussion
I always used to run my on super, but last few tanks have been standard unleaded (1999 4.0), and to be honest, I cant tell any difference.
Have heard a few say that it can make a difference depending on how the engine is set up (someone will probably be along with a more technical answer) but for everyday driving standard seems fine for me.
Have heard a few say that it can make a difference depending on how the engine is set up (someone will probably be along with a more technical answer) but for everyday driving standard seems fine for me.
KSV said:
thanks again
But thought HC meant High Lift Cam.
Colin
It does But thought HC meant High Lift Cam.
Colin
in fact not much chance of pinking with this engine as most of the compression is going down the exhaust at low speeds overcammed combined with moderate compression (stock) not a good mix 
I have tried both super & regular over the years and noticed f
k all difference running or power wise 
i stick the super in occasionally for its better detergents but that's all 
Simon says said:
KSV said:
thanks again
But thought HC meant High Lift Cam.
Colin
It does But thought HC meant High Lift Cam.
Colin
in fact not much chance of pinking with this engine as most of the compression is going down the exhaust at low speeds overcammed combined with moderate compression (stock) not a good mix I have tried both super & regular over the years and noticed fk all difference running or power wise i stick the super in occasionally for its better detergents but that's all 
My 4.0HC has run on Tesco Finest 95 for 2.5 years after I discovered the expensive stuff made naf all difference.
I quizzed Rob Robertson on all this when he fitted the Stealth cam.
In his words "95 is fine, after all it's a low compression engine"
Like Simon Says mine gets a tank of VPower once or twice a year just for the better detergent package.
ChimpanLucky said:
Simon says said:
KSV said:
thanks again
But thought HC meant High Lift Cam.
Colin
It does But thought HC meant High Lift Cam.
Colin
in fact not much chance of pinking with this engine as most of the compression is going down the exhaust at low speeds overcammed combined with moderate compression (stock) not a good mix I have tried both super & regular over the years and noticed fk all difference running or power wise i stick the super in occasionally for its better detergents but that's all My 4.0HC has run on Tesco Finest 95 for 2.5 years after I discovered the expensive stuff made naf all difference.
I quizzed Rob Robertson on all this when he fitted the Stealth cam.
In his words "95 is fine, after all it's a low compression engine"
Like Simon Says mine gets a tank of VPower once or twice a year just for the better detergent package.
the leak down test gave far better results though most jump for the bigger RV8's straight away but i reckon if you can hike the CR and get decent heads, lighten the fly etc on the baby 3.9 it will wail like a Banshee Simon says said:
ave even if you do a stock compression test on the HC engine the results are not impressive obviously because of the uncompromising cam profile the leak down test gave far better results though most jump for the bigger RV8's straight away but i reckon if you can hike the CR and get decent heads, lighten the fly etc on the baby 3.9 it will wail like a Banshee
Well that's been my thinking all along, I've been around the infernal combustion engine long enough to know the architecture of the shorter stroke 4 litre motor means it's destined to spin better (on the cheap). the leak down test gave far better results though most jump for the bigger RV8's straight away but i reckon if you can hike the CR and get decent heads, lighten the fly etc on the baby 3.9 it will wail like a Banshee The 25% of mass taken out of my stock flywheel & the Stealth cam massively helped towards releasing this potential.
What it needs now is an even better spark with a way to properly configure the advance & retard characteristics.
Something like MegaJolt should give a crisper throttle response, more torque and help the motor feel like it's spinning up even better.
Next step will be to play about with throttle cable cams, 1:1 liner from 800 - 2300 and then exponential from there on for that "Oooo she spins up nice" feeling.
Mostly just tricks to change the feel, but I've been around women long enough to know it's the feel that's the important bit
Watch this space
Simon says said:
Decent heads and reworked intake would be my next mod to release some proper HP rather than alternative throttle pulleys/quadrants it's it not a Moto X bike 
Muppetry answer Simon, obviously a set of decent heads & better breathing generally on the induction side would make a bigger difference.Decent heads = £850 + gaskets ect
Throttle cam = £30 max + an hour to fit & set it up
FYI there are hundreds cars that have been fitted with a throttle cams (since the year dot), it's not just for bikes mate.
For example I've seen LS1s that use a cable that rides on a cam which can be adjusted to give the throttle response as you like.
Its a cheap trick... but hey I'm cheap
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